S. Varadhan - Academia.edu (original) (raw)
Papers by S. Varadhan
Modeling the self-organization and collective behavior of dislocation ensembles is of primary con... more Modeling the self-organization and collective behavior of dislocation ensembles is of primary concern in this work. Two dislocation species are considered: excess dislocations seen as a man-ifestation of lattice incompatibility, and statistically distributed dislocations, which induce com-patible deformation. Conventional slip-based crystal plasticity is used to model the behavior and dynamics of the latter, while Field Dislocation Mechanics is employed to account for the former. Coupling the dynamics of both species proceeds along two reciprocal ways: spatial gradients in slip produced by mobile statistical dislocations leads to nucleation of excess dislocations, while excess dislocations contribute to forest hardening. Illustration is given to the evolution of mobile and excess dislocation density. Dislocation arrangements resulting from the model are presented.
Indian Journal of Clinical Biochemistry, 2008
After administration, ethanol and its metabolites go through the kidneys and are excreted into ur... more After administration, ethanol and its metabolites go through the kidneys and are excreted into urine. The kidney seems to be the only vital organ generally spared in chronic alcoholics. Therefore, we investigated the multiple effects of chronic ethanol exposure on renal function tests and on oxidative stress related parameters in the kidney. Chronic ethanol (1.6 g ethanol/ kg body weight/ day) exposure did not show any significant change in relative weight (g/ 100g body weight) of kidneys, serum calcium level or glutathione s-transferase activity. However, urea and creatinine concentration in serum, and TBARS level in kidney elevated significantly, while reduced glutathione content and activities of glutathione peroxidase, glutathione reductase and superoxide dismutase diminished significantly after 12 weeks of ethanol exposure. Catalase activity showed increased activity after 4 weeks of ethanol exposure and decreased activity after 12 weeks of ethanol exposure. Genesis of renal ultrastructural abnormalities after 12 weeks of ethanol exposure may be important for the development of functional disturbances. This study revealed that chronic ethanol exposure for longer duration is associated with deleterious effects in the kidney.
Indian Journal of Clinical Biochemistry, 2009
Alcohol consumption and health outcomes are complex and multidimensional. Ethanol (1.6g / kg body... more Alcohol consumption and health outcomes are complex and multidimensional. Ethanol (1.6g / kg body weight/ day) exposure initially affects liver function followed by renal function of 16-18 week-old male albino rats of Wistar strain weighing 200-220 g. Chronic ethanol ingestion increased in thiobarbituric acid reactive substances level and glutathione s-transferase activity; while decreased reduced gluatathione content and activities of catalase, glutathione peroxidase and glutathione reductase in a time dependent manner in the hemolysate. Though superoxide dismutase activity increased initially might be due to adaptive response, but decreased later. Elevation of serum nitrite level and transforming growth factor-b 1 activity indicated that long-term ethanol consumption may cause hepatic fibrosis and can elicit pro-angiogenic factors. However, no alteration in vascular endothelial growth factor-C activity indicated that ethanol consumption is not associated with lymphangiogenesis. Therefore, we conclude that long-term ethanol-induced toxicity is linked to an oxidative stress, which may aggravate to fibrosis and elevate pro-angiogenic factors, but not associated with lymphangiogenesis.
Indian journal of biochemistry & biophysics, 2009
Alcohol consumption is implicated in the genesis of a spectrum of liver abnormalities, which are ... more Alcohol consumption is implicated in the genesis of a spectrum of liver abnormalities, which are associated with a number of factors. In the present study, time-dependent effects of ethanol on cytokines (TNF-alpha, IL-2, IL-4, IL-10, IFN-gamma, VEGF-A and TGF-beta1) in serum, and blood oxidative stress parameters such as reduced glutathione content, TBARS level and activities of GPx, GR, GST, catalase and SOD in 8-10 weeks-old male BALB/c mice have been investigated. Ethanol administered @ 1.6 g/kg body wt/day significantly increased the activities of liver marker enzymes AST, ALT and ALP. Serum nitrite levels and haemolysate TBARS level also increased, while total antioxidant status in serum and GSH content in whole blood hemolysate decreased from 4th week onwards of exposure. In spite of the increased serum nitrite level and GST activity in the haemolysate, albumin level in serum, GPx and GR activities in haemolysate decreased after 12 weeks of exposure. Chronic ethanol treatment ...
Indian Journal of Clinical Biochemistry, 2009
Chronic pancreatitis, an irreversible inflammatory disease of the pancreas, is associated with th... more Chronic pancreatitis, an irreversible inflammatory disease of the pancreas, is associated with the replacement of the destroyed parenchyma by extended development of fibrosis. Despite marked progress in diagnostic tools, no consensus has been reached in diagnosis of chronic pancreatitis. In this study we examined the hematological and biochemical parameters among 40 chronic pancreatitis patients within 18 to 67 yrs. ESR level and ALP activity was elevated in 40% cases. Serum amylase activity increased in 32 patients and it showed significant correlation with ALP (r=0.458, p=0.003), p<0.001), p=0.002). Type IV collagen level in chronic pancreatitis also elevated (164.4 ± 55.5 ng/ ml) and showed negative significant correlation with calcium level (r= -0.505, p=0.001). However, no significant correlation was observed between amylase activity and type IV collagen (r=0.289, p= 0.07).
Quantum Field Theory, 1985
In their previous work on large deviations the authors always assumed the base process to be Mark... more In their previous work on large deviations the authors always assumed the base process to be Markovian whereas here they consider the base process to be stationary Gaussian. Similar large deviation results are obtained under natural hypotheses on the spectral density function of the base process. A rather explicit formula for the entropy involved is also obtained.
Theory of Probability & Its Applications, 1964
Physical Review Letters, 2007
Single crystals of ice subjected to primary creep in torsion exhibit a softening behavior: the pl... more Single crystals of ice subjected to primary creep in torsion exhibit a softening behavior: the plastic strain rate increases with time. In a cylindrical sample, the size of the radius affects this response. The smaller the radius of the sample becomes while keeping constant the average shear stress across a section, the softer the response. The size-dependent behavior is interpreted by using a field dislocation theory, in terms of the coupled dynamics of excess screw dislocations gliding in basal planes and statistical dislocations developed through cross slip occurring in prismatic planes. The differences in the results caused by sample height effects and variations in the initial dislocation microstructure are discussed.
Journal of the Mechanics and Physics of Solids, 2009
A model based on mesoscale field dislocation mechanics is presented for dislocationsolute interac... more A model based on mesoscale field dislocation mechanics is presented for dislocationsolute interaction, and applied to the study of strain-aging related instabilities-the Lü ders and Portevin-Le Chatelier phenomena-in single crystals. A dynamical description of dislocation-solute interaction provides local response. Elastic interaction and transport of polar dislocations, a measure of lattice incompatibility, impart spatial coupling. The 3D numerical results provide insight into the distribution of polar dislocations, stress, and strength in the region of the band, and also enable correlation of these quantities with the macroscopic stress-strain curve. The transition from homogeneous deformation to different kinds of propagating bands is captured as the applied strain rate is increased. The dynamical response has been characterized in terms of the correlation dimension of the reconstructed attractor, singular value decomposition and spectrum of Lyapunov exponents, and shown to be consistent with experiment. Other experimental observations, including the relationship of band speed to applied deformation rate, are also retrieved.
Journal of the American Statistical Association, 1985
... Lang: Complex Multiplication 256. Hormander: The Analysis of Linear Partial Differential Oper... more ... Lang: Complex Multiplication 256. Hormander: The Analysis of Linear Partial Differential Operators I 257. Hormander: The Analysis of Linear Partial Differential Operators II (continued after index) Page 5. ML Freidlin AD Wentzell Random Perturbations of Dynamical Systems ...
Journal of Statistical Physics, 2000
We consider the asymmetric simple exclusion process. We review some results in dimension d \ 3 co... more We consider the asymmetric simple exclusion process. We review some results in dimension d \ 3 concerning the fluctuation-dissipation theorem and we prove regularity of viscosity coefficients.
Journal of Geotechnical and Geoenvironmental Engineering, 2014
ABSTRACT
Modeling the self-organization and collective behavior of dislocation ensembles is of primary con... more Modeling the self-organization and collective behavior of dislocation ensembles is of primary concern in this work. Two dislocation species are considered: excess dislocations seen as a man-ifestation of lattice incompatibility, and statistically distributed dislocations, which induce com-patible deformation. Conventional slip-based crystal plasticity is used to model the behavior and dynamics of the latter, while Field Dislocation Mechanics is employed to account for the former. Coupling the dynamics of both species proceeds along two reciprocal ways: spatial gradients in slip produced by mobile statistical dislocations leads to nucleation of excess dislocations, while excess dislocations contribute to forest hardening. Illustration is given to the evolution of mobile and excess dislocation density. Dislocation arrangements resulting from the model are presented.
Indian Journal of Clinical Biochemistry, 2008
After administration, ethanol and its metabolites go through the kidneys and are excreted into ur... more After administration, ethanol and its metabolites go through the kidneys and are excreted into urine. The kidney seems to be the only vital organ generally spared in chronic alcoholics. Therefore, we investigated the multiple effects of chronic ethanol exposure on renal function tests and on oxidative stress related parameters in the kidney. Chronic ethanol (1.6 g ethanol/ kg body weight/ day) exposure did not show any significant change in relative weight (g/ 100g body weight) of kidneys, serum calcium level or glutathione s-transferase activity. However, urea and creatinine concentration in serum, and TBARS level in kidney elevated significantly, while reduced glutathione content and activities of glutathione peroxidase, glutathione reductase and superoxide dismutase diminished significantly after 12 weeks of ethanol exposure. Catalase activity showed increased activity after 4 weeks of ethanol exposure and decreased activity after 12 weeks of ethanol exposure. Genesis of renal ultrastructural abnormalities after 12 weeks of ethanol exposure may be important for the development of functional disturbances. This study revealed that chronic ethanol exposure for longer duration is associated with deleterious effects in the kidney.
Indian Journal of Clinical Biochemistry, 2009
Alcohol consumption and health outcomes are complex and multidimensional. Ethanol (1.6g / kg body... more Alcohol consumption and health outcomes are complex and multidimensional. Ethanol (1.6g / kg body weight/ day) exposure initially affects liver function followed by renal function of 16-18 week-old male albino rats of Wistar strain weighing 200-220 g. Chronic ethanol ingestion increased in thiobarbituric acid reactive substances level and glutathione s-transferase activity; while decreased reduced gluatathione content and activities of catalase, glutathione peroxidase and glutathione reductase in a time dependent manner in the hemolysate. Though superoxide dismutase activity increased initially might be due to adaptive response, but decreased later. Elevation of serum nitrite level and transforming growth factor-b 1 activity indicated that long-term ethanol consumption may cause hepatic fibrosis and can elicit pro-angiogenic factors. However, no alteration in vascular endothelial growth factor-C activity indicated that ethanol consumption is not associated with lymphangiogenesis. Therefore, we conclude that long-term ethanol-induced toxicity is linked to an oxidative stress, which may aggravate to fibrosis and elevate pro-angiogenic factors, but not associated with lymphangiogenesis.
Indian journal of biochemistry & biophysics, 2009
Alcohol consumption is implicated in the genesis of a spectrum of liver abnormalities, which are ... more Alcohol consumption is implicated in the genesis of a spectrum of liver abnormalities, which are associated with a number of factors. In the present study, time-dependent effects of ethanol on cytokines (TNF-alpha, IL-2, IL-4, IL-10, IFN-gamma, VEGF-A and TGF-beta1) in serum, and blood oxidative stress parameters such as reduced glutathione content, TBARS level and activities of GPx, GR, GST, catalase and SOD in 8-10 weeks-old male BALB/c mice have been investigated. Ethanol administered @ 1.6 g/kg body wt/day significantly increased the activities of liver marker enzymes AST, ALT and ALP. Serum nitrite levels and haemolysate TBARS level also increased, while total antioxidant status in serum and GSH content in whole blood hemolysate decreased from 4th week onwards of exposure. In spite of the increased serum nitrite level and GST activity in the haemolysate, albumin level in serum, GPx and GR activities in haemolysate decreased after 12 weeks of exposure. Chronic ethanol treatment ...
Indian Journal of Clinical Biochemistry, 2009
Chronic pancreatitis, an irreversible inflammatory disease of the pancreas, is associated with th... more Chronic pancreatitis, an irreversible inflammatory disease of the pancreas, is associated with the replacement of the destroyed parenchyma by extended development of fibrosis. Despite marked progress in diagnostic tools, no consensus has been reached in diagnosis of chronic pancreatitis. In this study we examined the hematological and biochemical parameters among 40 chronic pancreatitis patients within 18 to 67 yrs. ESR level and ALP activity was elevated in 40% cases. Serum amylase activity increased in 32 patients and it showed significant correlation with ALP (r=0.458, p=0.003), p<0.001), p=0.002). Type IV collagen level in chronic pancreatitis also elevated (164.4 ± 55.5 ng/ ml) and showed negative significant correlation with calcium level (r= -0.505, p=0.001). However, no significant correlation was observed between amylase activity and type IV collagen (r=0.289, p= 0.07).
Quantum Field Theory, 1985
In their previous work on large deviations the authors always assumed the base process to be Mark... more In their previous work on large deviations the authors always assumed the base process to be Markovian whereas here they consider the base process to be stationary Gaussian. Similar large deviation results are obtained under natural hypotheses on the spectral density function of the base process. A rather explicit formula for the entropy involved is also obtained.
Theory of Probability & Its Applications, 1964
Physical Review Letters, 2007
Single crystals of ice subjected to primary creep in torsion exhibit a softening behavior: the pl... more Single crystals of ice subjected to primary creep in torsion exhibit a softening behavior: the plastic strain rate increases with time. In a cylindrical sample, the size of the radius affects this response. The smaller the radius of the sample becomes while keeping constant the average shear stress across a section, the softer the response. The size-dependent behavior is interpreted by using a field dislocation theory, in terms of the coupled dynamics of excess screw dislocations gliding in basal planes and statistical dislocations developed through cross slip occurring in prismatic planes. The differences in the results caused by sample height effects and variations in the initial dislocation microstructure are discussed.
Journal of the Mechanics and Physics of Solids, 2009
A model based on mesoscale field dislocation mechanics is presented for dislocationsolute interac... more A model based on mesoscale field dislocation mechanics is presented for dislocationsolute interaction, and applied to the study of strain-aging related instabilities-the Lü ders and Portevin-Le Chatelier phenomena-in single crystals. A dynamical description of dislocation-solute interaction provides local response. Elastic interaction and transport of polar dislocations, a measure of lattice incompatibility, impart spatial coupling. The 3D numerical results provide insight into the distribution of polar dislocations, stress, and strength in the region of the band, and also enable correlation of these quantities with the macroscopic stress-strain curve. The transition from homogeneous deformation to different kinds of propagating bands is captured as the applied strain rate is increased. The dynamical response has been characterized in terms of the correlation dimension of the reconstructed attractor, singular value decomposition and spectrum of Lyapunov exponents, and shown to be consistent with experiment. Other experimental observations, including the relationship of band speed to applied deformation rate, are also retrieved.
Journal of the American Statistical Association, 1985
... Lang: Complex Multiplication 256. Hormander: The Analysis of Linear Partial Differential Oper... more ... Lang: Complex Multiplication 256. Hormander: The Analysis of Linear Partial Differential Operators I 257. Hormander: The Analysis of Linear Partial Differential Operators II (continued after index) Page 5. ML Freidlin AD Wentzell Random Perturbations of Dynamical Systems ...
Journal of Statistical Physics, 2000
We consider the asymmetric simple exclusion process. We review some results in dimension d \ 3 co... more We consider the asymmetric simple exclusion process. We review some results in dimension d \ 3 concerning the fluctuation-dissipation theorem and we prove regularity of viscosity coefficients.
Journal of Geotechnical and Geoenvironmental Engineering, 2014
ABSTRACT